Evaluation of poly (lactic-co-glycolic acid) nanoparticles to improve the therapeutic efficacy of paclitaxel in breast cancer.

Paclitaxel (PTX) is a cornerstone in the treatment of breast cancer, the most common type of cancer in women. However, this drug has serious limitations, including lack of tissue-specificity, poor water solubility, and the development of drug resistance. The transport of PTX in a polymeric nanoformulation could overcome these limitations. In this study, PLGA-PTX nanoparticles (NPs) were assayed in breast cancer cell lines, breast cancer stem cells (CSCs) and multicellular tumor spheroids (MTSs) analyzing cell cycle, cell uptake (Nile Red-NR-) and α-tubulin expression. In addition, PLGA-PTX NPs were tested using C57BL/6 mice, including a biodistribution assay. PTX-PLGA NPs induced a significant decrease in the PTX IC50 of cancer cell lines (1.31 and 3.03-fold reduction in MDA-MB-231 and E0771 cells, respectively) and CSCs. In addition, MTSs treated with PTX-PLGA exhibited a more disorganized surface and significantly higher cell death rates compared to free PTX (27.9% and 16.3% less in MTSs from MCF-7 and E0771, respectively). PTX-PLGA nanoformulation preserved PTX's mechanism of action and increased its cell internalization. Interestingly, PTX-PLGA NPs not only reduced the tumor volume of treated mice but also increased the antineoplastic drug accumulation in their lungs, liver, and spleen. In addition, mice treated with PTX-loaded NPs showed blood parameters similar to the control mice, in contrast with free PTX. These results suggest that our PTX-PLGA NPs could be a suitable strategy for breast cancer therapy, improving antitumor drug efficiency and reducing systemic toxicity without altering its mechanism of action.